Fast trimming of electro-optic polymer waveguide Y-branches by postphotobleaching for tuning the power splitting ratio

Abstract

We present a novel post-fabrication laser trimming technique to adjust the power splitting ratio of strip waveguide Y-branches made in thermally crosslinked electro-optic polymers. The trimming is based on the irreversible index change due to photobleaching. Our method uses simple equipment and the process takes only a few seconds. Waveguides made by both reactive ion etching and photobleaching are trimmable. An adjustable range of the splitting ratio as wide as is achieved with less than 0.2 dB of excess loss. This in situ trimming technique is effective for both the TE and TM modes of the waveguide and is very suitable for automated device processing.

Polymeric Electro-optic Modulators: From Chromophore Design to Integration with Semiconductor Very Large Scale Integration Electronics and Silica Fiber Optics

“…For waveguide devices, imperfections can seriously affect device performance such as the splitting ratio of Y-junction splitters, the extinction ratio of Mach−Zender modulators, and the coupling constant of directional coupler switches. Trimming techniques which can tune device performance will reduce device cost, improve performance, and increase fabrication yield. ,− For waveguide devices containing photobleachable chromophores (e.g., a Mach−Zender modulator fabricated from PU-DR19) postfabrication in situ trimming can be employed to improve performance. ,− …”

“…Trimming techniques which can tune device performance will reduce device cost, improve performance, and increase fabrication yield. 28,[72][73][74] For waveguide devices containing photobleachable chromophores (e.g., a Mach-Zender modulator fabricated from PU-DR19) postfabrication in situ trimming can be employed to improve performance. 28,[72][73][74] We have used such trimming with a Mach-Zender modulator (see Figure 30).…”

Fabrication of polymer integrated optical microring resonator with photobleaching method

“…Using the relative refractive index difference of ∆ =3.1% (which is a typical value of the polymer film of the AJL8/APC material) between the core and cladding of the straight waveguide and the ring, the widths of the waveguide and the ring must be selected as 4 m µ to achieve single-mode operation. To The microring resonator was fabricated based on the polymer film of the AJL8/APC material using the photobleaching technique [7]. The polymer film was prepared by the spin-coating method.…”

Polymeric electro-optic materials: optimization of electro-optic activity, minimization of optical loss, and fine-tuning of device performance

“…9 While operation at communication wavelengths causes minimal material damage for many chromophorecontaining polymers, irradiation into the interband electronic ͑charge transfer͒ transition can be used to effect photochemical modification of the polymeric materials and the properties of circuit elements such as power splitters. 10 Thus, photochemical processing using a translatable microscopic focusing of light can be used to fine tune the performance of electro-optic devices such as Mach-Zehnder modulators and the voltage-controlled rf photonic phaseshifter described recently by Udupa and coworkers. 3,11 Since we have discussed elsewhere 1,12 using lattice hardening chemical reactions to impart thermal and photochemical stability to polymeric electro-optic materials, we do not repeat that discussion here.…”

“…Most aspects of the fabrication of multimodulator circuits integrated with VLSI electronics and silica communication fibers have been discussed at length elsewhere 1,3,8 and are thus not reviewed here. However, recent advances in the transitioning between passive and active waveguides 9 and in the trimming of the performance of optical splitters 10 are noteworthy and are commented on briefly.…”